Similar presentations

2 Presentation Outline Importance of benthic invertebratesPopulation based modelApproachLimitationsIndividual based modelCombining with population modelGenetic variabilityConcluding Remarks

3 Benthic InvertebratesImportant components of estuarine and coastal food webs – sentinel species, many long livedProvide coupling between benthic and pelagic systemsPost-settlement and larval phases of life historyFiltering waterRegulate food concentrations (phytoplankton)Nutrient cyclingShellfish important to carbonate balanceMany are commercially importantImportant to local history and culture

4 Benthic InvertebratesIncluded in models as loss/gain term via boundary conditionsLoss of phytoplankton via filtration rateNutrient addition termPopulation that grows and declines in response to various forcing functionsCoupled circulation-biological model focused on larvae - usually transport pathwaysCoupled circulation-biological model that includes larvae and post-settlement populationsImportance of understanding ecology, physiology and life history of organism

5 General CharacteristicsMost models track energy – given by difference between assimilation and respirationReproduction is energy loss but provides recruitsMortality – natural, disease, predation, starvationMovement – pelagic phase to life history – need circulationRange of responses within species in rates – genetic variabilityMultiple species – focus on ones with data

6 Population Dynamics Modeling - The PastPopulation-based model of the average individualBased on animal physiologyParameterized for average physiologyAllows projection of responses to environmental conditions

7 Aspects of Population DynamicsAnimal growsSomatic tissueReproductive tissueReproduces – biological and environmental cuesEnvironmental inputsAnimal filtration rate sets up assimilation and respirationAnimal can gain and loose massModel usually in terms of energy or carbon

10 Shrinkage due to poor environmental conditionsReproductive tissue accounts for 30-50% of body weightSpawning is a loss of mass and energy for size classLarvae provide new recruits and connect to pelagic system

12 oyster population size structure Time history of Results – what learnedSimulated change inoyster population sizestructureTime history ofreproductive tissue andoccurrence of spawningevents

13 LimitationsAverage individual – does not allow consideration of variability in physiological responsesLarvae incorporated as a loss of mass and input of mass to smallest size class – not altering characteristics of post-settlement populationGain/loss in weight requires again/loss in length

14 Population Dynamics Modeling The Recent PresentAnimalIndividual-based modelMultiple cohorts of phenotypically varying individualsAllows phenotypic variation to determine population response to environmentAge-size decoupled so that age-frequency and size-frequency distributions can be independently described

19 Investigate effects of environmental conditions on clam weight and lengthStarvation period imposed in years 3-5 via low food conditionsChange in clam condition over timeManagement implications

20 Successful How to extend beyond individual?Apply a Gaussian function to producea distribution of individuals with rangeof characteristicsSuccessfulIndividual hard clam results are extended to cohort and populationlevels

23 LimitationsPopulation variability is based on probability distributionCannot determine cause and effect of variabilityIntroduction of new traits and/or modifications to existing traits not possibleWant to be able to track genetic variability

25 Characteristics of OystersHigh fecundity – 106 eggs per spawn with multiple spawnings per seasonProtandic – male when young, small size and become female when older and largerSex ratio of the population changes as it agesHigh load of lethal mutationsPotentially subject to sweepstakes reproductive success events

26 Inclusion of Explicit GeneticsTrack trajectory of individual alleles over time which gives a measure of genetic drift and loss of allelesEffective population numberIntroduction of new genetic traitsRelevance – pH effects,disease resistance,warming temperatures

28 Population trajectory Population characteristics AND Model frameworkprovidesPopulation trajectoryPopulation characteristicsANDGenetic compositionExample ApplicationSimulate introduction of specific genes into a populationAllele frequency on each chromosome

36 Concluding Remarks Understanding and tools allowconsideration of interactions of ecology,biology and geneticsShellfish models are extendable to other invertebrate species – understand species and have dataConsider combined effects of environment, growth, behavior in projections of effects of climate change

About project

Feedback

To ensure the functioning of the site, we use cookies. We share information about your activities on the site with our partners and Google partners: social networks and companies engaged in advertising and web analytics. For more information, see the Privacy Policy and Google Privacy &amp Terms.
Your consent to our cookies if you continue to use this website.